* introduce storage types
* fix line width
* improve doc
* typo
* Apply suggestions from code review
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>
* remove redundant function
* some more doc improvment
* disallow: some value on empty with option query
tests are update to still test default value is used when it is supposed
to be used.
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>